Water Resources Research Act Program

Details for Project ID 2007NJ146B

Biogeochemistry of Pb transformations mediated by phosphate-releasing bacteria

Institute: New Jersey
Year Established: 2007 Start Date: 2007-03-01 End Date: 2008-02-29
Total Federal Funds: $29,987 Total Non-Federal Funds: $49,715

Principal Investigators: Nathan Yee

Project Summary: Pb is a toxic heavy metal contaminant found in many New Jersey contaminated sites. The subsurfacetransport of Pb occurs in the solution phase, therefore the desorption of Pb ions and the solubility of Pb minerals can affect its mobility and migration. Many Pb contaminated soils contain soluble Pbcarbonate minerals, which are unstable under acidic to circumneutral pH conditions. Recently, we have discovered a bacterium isolated from a New Jersey contaminated soil that can transform cerussite(PbCO3) into highly insoluble Pb-phosphate minerals. The mechanisms controlling this novel mineral transformation process are currently unknown. In this study, we propose to apply a combination of macroscopic, microscopic, and spectroscopic experiments to elucidate the rates and mechanisms of Pbphosphate biomineralization. We hypothesize that soil bacteria can hydrolyze organic phosphorus compounds and release inorganic phosphate which react with aqueous and solid-phase lead to precipitate Pb-phosphate minerals. There are three specific goals for the proposed work. First, we will evaluate the ability of our bacterial isolate to release inorganic phosphate from organic phosphorus compounds. Second, we will quantify the rates of microbially induced Pb mineral transformation. Finally, we will characterize the reaction products formed by this process using electron microscopy, Xray diffraction, and extended X-ray absorption fine structure spectroscopy. The results of this research will elucidate a microbial-mediated mineral transformation process that has important implications for the sequestration of toxic metals in contaminated soils and sediments.